Date Published: July 1, 2017
Publisher: American Physiological Society
Author(s): Hanne C. Gadeberg, Cherrie H. T. Kong, Simon M. Bryant, Andrew F. James, Clive H. Orchard.
This study shows that in contrast to the rat, mouse ventricular Na+/Ca2+ exchange current density is lower in the t-tubules than in the surface sarcolemma and Ca2+ current is predominantly located in the t-tubules. As a consequence, the t-tubules play a role in recovery (autoregulation) from reduced, but not increased, sarcoplasmic reticulum Ca2+ release.
The present study was designed to investigate the role of the t-tubules in Ca2+ autoregulation in mouse ventricular myocytes. The data show that the majority of ICa occurs in the t-tubules, whereas, in contrast to rat myocytes, INCX occurs mainly at the surface sarcolemma and the hysteresis between Ca2+ and INCX persists after DT. Although autoregulation to steady state occurred after DT, the time course of recovery was slower during recovery from decreased SR Ca2+ release but, interestingly, not from increased SR Ca2+ release. This suggests that t-tubules play a role in recovery from decreased, but not increased, SR Ca2+ release, which may reflect the localization of ICa and INCX.
This work was supported by British Heart Foundation Grants PG/14/65/31055 and RG/12/10/29802.
No conflicts of interest, financial or otherwise, are declared by the authors.
H.C.G. performed experiments; H.C.G. and C.H.K. analyzed data; H.C.G., S.M.B., A.F.J., and C.H.O. interpreted results of experiments; H.C.G. prepared figures; H.C.G. and C.H.O. drafted manuscript; H.C.G., C.H.K., S.M.B., A.F.J., and C.H.O. edited and revised manuscript; A.F.J. and C.H.O. conceived and designed researc
h; A.F.J. and C.H.O. approved final version of manuscript.